Actor Ethan Hawke and actress Patricia Arquette attend a screening of “Boyhood” July 7 in New York.

“Before Sunrise” and its two sequels, “Before Sunset” and “Before Midnight,” follow a romance over a period of nearly two decades, as its stars Hawke and Julie Delpy age before audiences’ eyes.

In “Boyhood,” Linklater brings his fascination with memory and time to his most ambitious project yet. Over a period of 12 years, he filmed a coming-of-age tale as its star, Ellar Coltrane, truly came of age — growing from six to 18 on screen.

“‘Boyhood’ is to growing up what the ‘Before’ trilogy is to romantic love. It’s using time as a kind of clay. You can get at something kind of profound if you explore it over a long period of time,” Hawke said in a recent phone interview.

“A lot of movies are fake because they’re trying to create this one moment that crystallizes growing up,” he added. “It’s always kind of a lie. Our lives never really have a clear narrative like that. The way that Rick uses time, it allows for something more real and more believable in the storytelling.”

Hawke, 43, plays a father divorced from Patricia Arquette’s character, who is raising their two kids Mason (Coltrane) and Samantha (Lorelei Linklater, the director’s daughter). The film explores parenthood as well as boyhood — while Hawke plays a fun dad, he isn’t always present, and while Arquette’s character works hard to improve her kids’ lives, she makes mistakes.

While Mason’s experiences will feel familiar to many viewers, Linklater tells the story unconventionally. Moments that are typically considered to be pivotal — losing your virginity or your mom getting married — occur off-screen.

“I feel it’s essential to the movie’s success,” said Hawke. “The mistake a lot of people would have made would be to do the first kiss or the first time you got drunk. I think this movie works a lot like the way memory does. You never really know what Patricia Arquette and my relationship is like or why we got divorced or anything like that, but kids never do. … It’s not really a big deal in their lives. Of course, it would be in hindsight.

“When you’re really living it, somehow, losing your virginity is not actually the most interesting thing that happens. It’s the first time you really connected with a lover.”

Linklater and the cast and crew met every year to film up to 15 minutes of the movie. Hawke said that in the months leading up to shooting, Linklater and he would chat on the phone about what was going on with his character or Coltrane’s.

“It was kind of a forum for me to explore all the things I was going through as a father. That’s one thing about being a dad, is that you still relate to being a kid, too. So I’m seeing that story from both points of view now,” he said.

For example, in one scene Hawke’s character is driving his two kids around and getting only one-word answers to his questions. The father gets increasingly frustrated as his kids refuse to make conversation.

“He pulls over the car, and they basically teach him that he has to try to let it happen more naturally,” said Hawke with a laugh. “That’s very much something that happened with my kids. I would tell Rick about it and he’d go, ‘Oh man, we’ve got to put that in.”’

Coltrane was cast in 2002 at age six with precious little acting experience. It was fascinating to watch him develop as an actor as he grew up, said Hawke.

“In the beginning he’s just a little boy, having fun and wanting to be an actor, like lots of little kids,” he said. “But as the movie grew on, he began to understand the process that we were going through and he became a real creative contributor, same with Lorelei, who played the sister. It was just fun watching them mature as artists.”

Actor Ethan Hawke and actress Patricia Arquette attend a screening of “Boyhood” July 7 in New York.